• Physical Therapy Korea
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• v.1 no.1
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• pp.75-82
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• 1994

The purpose of this study is to determine cardiovascular reponses to concentric, eccentric and isometric exercise applied to the knee extensor muscle group. Exercise types studied were concentric, eccentric and isometric. The subjects were sixty healthy male volunteers who had no hypertension or cardiac disease. Heart rate, systolic and diastolic blood pressure were recorded prior to starting exercise. The subjects also performed 10RM on right lower extremity. A N-K table was used for three exercises to right knee extensors. Each exercise was selected randomly and applied to each subject 10 times in a 10 second. After each exercise, heart rate, systolic and diastolic blood pressure were recorded immediately. Findings were as follows concectric contractions had a greater effect on the increase of systolic blood pressure and heart rate than eccentric or isometric contractions. Diastolic blood pressure is influenced only by isometric contractions. Eccentric contractions have less effect on the increase of systolic blood pressure and heart rate than concentric or isometric contractions. We hope that the results of this experiment can be adapted to exercise programs for patients with cardiac disease.

• Physical Therapy Korea
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• v.14 no.4
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• pp.1-6
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• 2007

This study examined the effects of hold-relax with agonist contraction (HR-AC) on the symptoms of delayed onset muscle soreness (DOMS) induced by intensive eccentric exercise of the non-dominant biceps brachii. Ten men (mean age=26.7 yrs, mean height=172.1 cm, mean weight=66.2 kg) and ten women (mean age=27.4 yrs, mean height=165.9 cm, mean weight=60.7 kg) who had not participated in a regular exercise program for the upper extremities in the previous six months were randomly assigned to one of two experimental groups: the HR-AC group, or the control group. We measured joint range of motion (ROM), maximal voluntary isometric contraction (MVIC), and muscle soreness before eccentric exercise, and 24, 48, and 72 hours after eccentric exercise. The subjects in the HR-AC group received the HR-AC technique in the non-dominant biceps brachii. The HR-AC technique was applied 24 and 48 hours after eccentric exercise. There was no significant difference between the HR-AC and the control group. However, the HR-AC group, compared to the control group, had a significant difference between the time points of the various parameters. Increased ROM (p<.05), decreased muscle soreness (p<.05), and reduced MVIC (p<.05) were found in the HR-AC group after 72 hours. Decreased ROM (p<.05) and MVIC (p<.05), and increased muscle soreness (p<.05) were observed in the control group. These findings suggest that the HR-AC technique effectively reduces muscle soreness and increases ROM 72 hours after eccentric exercise.

• The Journal of Korean Physical Therapy
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• v.22 no.2
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• pp.25-30
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• 2010

Purpose: Behavior and movement are accomplished by voluntary contractions of skeletal muscles. There are three types of muscle contractions: concentric, isometric and eccentric. The aim of our study was to determine whether there is a difference in the cortical activation pattern between concentric contraction and eccentric contraction of the wrist extensor muscle. Methods: Four healthy right-handed volunteers without any previous history of physical or neurological illness were recruited. fMRI scanning was done during 4 repeated blocks of concentric and eccentric exercise of the wrist joint. Subjects exercised for 12 seconds and then rested for 12 seconds before beginning the second set of exercises. To determine the excitability of cortical neurons during exercise, voxel count and intensity index were analyzed. Results: For right hand movements, when concentric contractions of the right wrist were done, only the left primary motor area was activated. In contrast, during eccentric contraction, both the primary motor area and secondary motor area were activated. For left hand movements, both concentric and eccentric contractions induced only the supplementary motor cortex and the contralateral primary motor cortex. Conclusion: During eccentric contractions, both the primary motor area and secondary motor area are activated in ipsilateral and contralateral brain areas. Thus, eccentric contractions require more complex and difficult movements than concentric contractions do.

• Korean Journal of Applied Biomechanics
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• v.18 no.4
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• pp.21-30
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• 2008

The purpose of this study was to investigate changes in mechanical properties of human tibialis anterior following eccentric exercise. Healthy subjects (n=12) performed 120 maximum eccentric contraction of ankle dorsiflexor. Before and 1- and 24- hour after the eccentric exercise, ankle dorsiflexion moment-angle relationships were obtained. Along with significant decrease in maximum isometric muscle strength, the shift of the optimum ankle joint angle toward the longer muscle length direction was observed, independent of the ranges of motion of the eccentric exercise. The results of this study demonstrated that eccentric exercise-induced micro muscle damage(Morgan & Allen, 1999) does rut seem to be a sole mechanism of eccentric contraction-induced muscle damage, suggesting further investigation for the better understandings of this phenomenon.

• Korean Journal of Applied Biomechanics
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• v.21 no.2
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• pp.189-196
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• 2011

The purpose of this study was to verify the difference in biomechanical variation and pattern of the lower limb between planned and unexpected termination, which is related to the prevention of fatal fall in the elderly. Therefore, selected twenty subjects for each group which composed of females(age: $73.5{\pm}4.63$ year, height: $153.2{\pm}6.46$ cm, body mass: $58.98{\pm}5.82$ kg) and women(age: $23.4{\pm}2.5$ year, height: $164.65{\pm}3.9$ cm, body mass: $58.47{\pm}5.53$ kg) in their twenties. As a result, lower limb's extension moment and power were increased significantly in statistics(p<.05). Also, knee joint power showed instant changes from concentric contraction to eccentric contraction and hip joint power from eccentric contraction to concentric contraction. During unexpected termination there were dramatical increase in eccentric contraction and power(p<.05). In both planned and unexpected termination, ankle joint moment were higher in young group, but the moment of the hip joint were higher in the elderly group(p<.05). In contrast to younger group, there were no changes in knee extension moment in elderly group(p<.05). but showed relatively higher hip joint extension moment and power(p<.05).

• The Journal of Korean Physical Therapy
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• v.20 no.1
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• pp.1-9
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• 2008

Purpose: This study examined the effects of pre-eccentric exercise to the quadriceps for the prevention of delayed onset muscle soreness (DOMS) and recovery of muscular function, depending on the training intensities. Methods: Subjects were divided into one of three groups that control group, a low intensity eccentric exercise group (LIEE group) and a high intensity eccentric exercise group (HIEE group). Subjects who underwent pre-eccentric exercise undertook exercise at an intensity of 25% and 75% of maximal voluntary contractions, respectively. After undertaking pre-eccentric exercise for eight weeks, eccentric exercise was applied again to induce DOMS. Measurements were conducted to examine pain and muscular function changes before, immediately after, after the induction of DOMS, and at the first, third, fifth and seventh days after the induction of DOMS. Results: Subjects who underwent pre-eccentric exercise showed a significant difference from the control group for the changes in the visual analogue scale (VAS) pain threshold, pressure pain threshold and muscle thickness by isometric contraction from measuring DOMS, and in particular, pain threshold by isometric contraction had remarkable effect in the LIEE group of subjects. For the change of the root mean square values using mechanomyography (MMG) as the measurement of muscular function recovery, subjects who had undertaken pre-eccentric exercise group showed a significant difference as compared to the control group. Conclusion: Pre-eccentric exercise was very effective in preventing and recovering delayed onset muscle soreness and was helpful to prevent and recover from decreased muscular function. The difference based on the intensity of exercise was not great, but it was more effective in the low intensity eccentric exercise group of subjects. Therefore, it can be considered that pre-eccentric exercise has a high application value as a physical therapy intervention for prevention and rehabilitation of sports injuries.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.1 no.1
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• pp.17-29
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• 2003

This study was investigated the effects on functional recovery of eccentric exercise-induced muscle damage by phonophoresis transdermal permeation of piroxicam gel and observed the change of amplitude at muscle action potential. Through eccentric exercise-induced muscle damage, performed healthy men and women take eccentric resistance exercise and measured action, potentials. The subjects were divided into three groups of four men each 24 hour, 48 hour, 72 hour. The results of this were as follows: 1. Change of maximal action potential at maximal voluntary contraction : The phonophoresis group was increase more than control group and gel group. 2. Change of average action potential at maximal voluntary contraction : The gel group was increase more than control group and phonophoresis group. 3. Change of maximal action potential at pain subthreshold voluntary contraction : The phonophoresis group was increase more significantly than control group and gel group. 4. Change of average action potential at pain subthreshold voluntary contraction : The phonophoresis group was increase more significantly than control group and gel group. In conclusion, the change of muscle action potential amplitude by eccentric exercise-induced muscle damage showed that the phonophoresis by pulsed ultrasound of piroxicam gel was improved the recovery of muscle function.

• The Journal of Korean Physical Therapy
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• v.28 no.3
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• pp.212-216
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• 2016

Purpose: The current study seeks to identify the relationship between torque values of the quadriceps and muscle activity during isometric and isokinetic exercises. Methods: The subjects of the study included 29 healthy individuals 17 men and 12 women) who took part in isometric and isokinetic exercises that utilized the quadriceps. The isometric exercises were performed three times each at 4 different angles (0, 30, 60, and 90 degrees). For the isokinetic exercises, concentric contraction and eccentric contraction were undertaken three times each at two angular velocities (30 and 60 degrees). Results: The muscle activity of the quadriceps during the isometric exercises showed significant differences at the 30, 60, and 90 degree angles. During the concentric contractions and eccentric contractions, muscle activity at the peak torque of the quadriceps indicated significant differences in vastus medialis, vastus lateralis, and rectus femoris at angular velocities of 30 and 60 degrees. Conclusion: When applied clinically based on the biomechanical analysis of the current study, it is possible to anticipate and selectively strengthen muscles with isometric and isokinetic exercises for not only healthy adults and professional athletes, but also for those who experience limited knee movement for long periods following knee surgeries.

• PNF and Movement
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• v.2 no.1
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• pp.25-33
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• 2004

Purpose : The purpose of this article is to summarize the characteristics of isotonic combination. Method : Some studies of the motor unit activation patterns during isometric, concentric, and eccentric actions, neural strategies in the control of muscle force, and concentric versus combined concentric-eccentric training were reviewed. Results & Conclusions : Eccentric torque may be relatively higher than concentric torque for two potential reasons: 1) stretch responses in the antagonist are not elicited to restrain the motion as can occur concentrically and 2) stretch responses in the agonist may augment eccentric torque production. Concentric-eccentric training has a greater influence on functional capacity than that of concentric training. Both maximal force and average force throughout the motion were significantly higher when the dynamic action was started with preactivation as compared to the mode without preactivation. The peak torques observed during the concentric phase of the eccentric-concentric muscle actions were higher than those noted in the pure concentric contraction.

• Physical Therapy Rehabilitation Science
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• v.7 no.4
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• pp.154-163
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• 2018

Objective: The purpose of this study was to investigate the effects of eccentric contraction training (ECT) and concentric contraction training (CCT) on the muscle thickness (MT), muscle strength (MS) and delayed onset of muscle soreness (DOMS) of the lower extremities in persons with chronic stroke. Design: Randomized controlled trial. Methods: Thirty persons with chronic stroke were randomly assigned to the ECT or the CCT group. The ECT was performed in a specially designed system of eccentric contraction of both legs and, the CCT was performed using a traditional stepper system for concentric contraction of both legs. The training was performed for 30 min/times, 3 times/wk for 6 weeks. Rehabilitation ultrasound imaging was used to measure MT of the vastus medialis/lateralis (VL), and soleus (SOL), a digital muscle tester was used to measure MS, and a visual analog scale was used to assess DOMS. Results: In the ECT group, MT was significantly improved except for SOL resting (p<0.01). In the CCT group, the MT was significantly improved except for VL contraction (p<0.05). The MS was significantly improved in both groups, especially in the ECT group (p<0.01). In the ECT group, muscle soreness was highest in the first week after training but gradually decreased, and in the CCT group, it was highest in the second week of training but gradually decreased (p<0.01). Conclusions: ECT can improve lower limb MT, MS, and DOMS of chronic stroke survivors. Therefore, it is recommended that ECT be used in the rehabilitation of persons with chronic stroke.